Untitled Flashcards Set

Volcano

A mountain formed by the eruption of magma/lava.

Active Volcanoes

Currently erupting or show signs of erupting, approximately 800 active volcanoes exist.

Convergent Plate Boundaries

Major locations for volcanoes found mainly at ocean-continent and continent-convergent boundaries.

Hotspot

An area where magma can rise through the mantle; examples include Hawaii and Yellowstone.

Viscosity of Magma

A measure of a magma's resistance to flow; affected by chemical composition, temperature, and amount of volatiles.

Pahoehoe Lava

A type of lava flow with a smooth, textured surface.

Aa Lava

A type of lava flow characterized by a sharp, fragmented surface.

Pyroclastic Material

Erupted material from high viscosity eruptions, including ash and rock.

Shield Volcano

A type of volcano that erupts basaltic lava, exemplified by those in Hawaii.

Cinder Cone Volcano

The smallest type of volcano, usually characterized by a single vent eruption.

Composite Volcano

Volcanoes with high viscosity magma that can have explosive eruptions; examples include Mount St. Helens.

Caldera

A large volcanic depression formed after a volcano collapses following a large eruption; an example is Crater Lake.

Lahar

A destructive volcanic mudflow that occurs when volcanic materials mix with water.

Fault

A fracture in the Earth's crust along which movement has occurred.

Strike-Slip Fault

A fault where the motion is horizontal, with one side sliding past the other.

Dip-Slip Fault

A fault where motion is vertical, with hanging walls and footwalls.

Isostasy

The equilibrium of the Earth's crust floating on the mantle, which is affected by loading and unloading.

Principle of Superposition

In an undeformed sequence of strata, the oldest layers are at the bottom and the youngest at the top.

Principle of Original Horizontality

The layers of sediment are typically deposited in a horizontal position.

Law of Cross-Cutting Relationships

Any geological feature that cuts across another is younger than the feature it cuts.